#include <defs.h>
#include <memlayout.h>
#include <mmu.h>
#include <param.h>
#include <proc.h>
#include <syscall.h>
#include <types.h>
//
#include <x86.h>

// User code makes a system call with INT T_SYSCALL.
// System call number in %eax.
// Arguments on the stack, from the user call to the C
// library system call function. The saved user %esp points
// to a saved program counter, and then the first argument.

// Fetch the int at addr from the current process.
int fetchint(uint addr, int *ip) {
	struct proc *curproc = myproc();

	if (addr >= curproc->sz || addr + 4 > curproc->sz)
		return -1;
	*ip = *(int *)(addr);
	return 0;
}

// Fetch the nul-terminated string at addr from the current process.
// Doesn't actually copy the string - just sets *pp to point at it.
// Returns length of string, not including nul.
int fetchstr(uint addr, char **pp) {
	char *s, *ep;
	struct proc *curproc = myproc();

	if (addr >= curproc->sz)
		return -1;
	*pp = (char *)addr;
	ep = (char *)curproc->sz;
	for (s = *pp; s < ep; s++) {
		if (*s == 0)
			return s - *pp;
	}
	return -1;
}

// Fetch the nth 32-bit system call argument.
int argint(int n, int *ip) {
	return fetchint((myproc()->tf->esp) + 4 + 4 * n, ip);
}

// Fetch the nth word-sized system call argument as a pointer
// to a block of memory of size bytes.  Check that the pointer
// lies within the process address space.
int argptr(int n, char **pp, int size) {
	int i;
	struct proc *curproc = myproc();

	if (argint(n, &i) < 0)
		return -1;
	if (size < 0 || (uint)i >= curproc->sz || (uint)i + size > curproc->sz)
		return -1;
	*pp = (char *)i;
	return 0;
}

// Fetch the nth word-sized system call argument as a string pointer.
// Check that the pointer is valid and the string is nul-terminated.
// (There is no shared writable memory, so the string can't change
// between this check and being used by the kernel.)
int argstr(int n, char **pp) {
	int addr;
	if (argint(n, &addr) < 0)
		return -1;
	return fetchstr(addr, pp);
}

extern int sys_chdir(void);
extern int sys_close(void);
extern int sys_dup(void);
extern int sys_exec(void);
extern int sys_exit(void);
extern int sys_fork(void);
extern int sys_fstat(void);
extern int sys_getpid(void);
extern int sys_kill(void);
extern int sys_link(void);
extern int sys_mkdir(void);
extern int sys_mknod(void);
extern int sys_open(void);
extern int sys_pipe(void);
extern int sys_read(void);
extern int sys_sbrk(void);
extern int sys_sleep(void);
extern int sys_unlink(void);
extern int sys_wait(void);
extern int sys_write(void);
extern int sys_uptime(void);

extern int sys_ioctl(void);
extern int sys_socket(void);
extern int sys_connect(void);
extern int sys_bind(void);
extern int sys_listen(void);
extern int sys_accept(void);
extern int sys_recv(void);
extern int sys_send(void);
extern int sys_recvfrom(void);
extern int sys_sendto(void);

static int (*syscalls[])(void) = {
	[SYS_fork] sys_fork,
	[SYS_exit] sys_exit,
	[SYS_wait] sys_wait,
	[SYS_pipe] sys_pipe,
	[SYS_read] sys_read,
	[SYS_kill] sys_kill,
	[SYS_exec] sys_exec,
	[SYS_fstat] sys_fstat,
	[SYS_chdir] sys_chdir,
	[SYS_dup] sys_dup,
	[SYS_getpid] sys_getpid,
	[SYS_sbrk] sys_sbrk,
	[SYS_sleep] sys_sleep,
	[SYS_uptime] sys_uptime,
	[SYS_open] sys_open,
	[SYS_write] sys_write,
	[SYS_mknod] sys_mknod,
	[SYS_unlink] sys_unlink,
	[SYS_link] sys_link,
	[SYS_mkdir] sys_mkdir,
	[SYS_close] sys_close,

	[SYS_ioctl] sys_ioctl,
	[SYS_socket] sys_socket,
	[SYS_connect] sys_connect,
	[SYS_bind] sys_bind,
	[SYS_listen] sys_listen,
	[SYS_accept] sys_accept,
	[SYS_recv] sys_recv,
	[SYS_send] sys_send,
	[SYS_recvfrom] sys_recvfrom,
	[SYS_sendto] sys_sendto,
};

void syscall(void) {
	int num;
	struct proc *curproc = myproc();

	num = curproc->tf->eax;
	if (num > 0 && num < NELEM(syscalls) && syscalls[num]) {
		curproc->tf->eax = syscalls[num]();
	} else {
		cprintf("%d %s: unknown sys call %d\n",
				curproc->pid, curproc->name, num);
		curproc->tf->eax = -1;
	}
}
